Lethality of Civilian Active Shooter Incidents With and Without Semiautomatic Rifles in the United States

Semiautomatic rifles have been used in some of the largest active shooter incidents in US history. The weapons were banned in 1994 under the federal assault weapons ban but were reintroduced to the public marketplace in 2004. Currently, there are no comprehensive assessments of injuries from different types of firearms. We compared the number of persons wounded, killed, and either wounded or killed during active shooter incidents with and without semiautomatic rifles.